Our head mentor is pressuring us to make the switch from using aluminum to carbon fiber completely, and by completely I mean it, use it for cylinders profiles etc. I tried to convince him that we should add carbon fiber to our arsenal, but he wants to switch aluminum with CF completely. We would like to hear your thoughts about how we should proceed with our mentor.
Sounds very excessive. Learn how to use it, but arbitrarily making everything cf is pretty silly.
I agree with you on this one. Teams who make decisions like this also tend to be optimizing in the wrong areas.
Tell your mentor that until you can consistently have a winning robot, making more than a few components out of CF is putting effort into the wrong areas of your robot and build/design process. CF also should be handled as a dangerous material in my personal opinion. I don’t think enough teams who use it do it with enough safety measures for dust and splinters. (Just my opinion)
No its flammable and conductive. Also the particulates you create when machining carbon fibre are not really safe to breathe.
Does your head mentor also want to board a submarine made out of CF? It’s a useful material, but it’s way more useful in some applications than others. Aluminum is still useful, too. A balance of both in their respective use cases is ideal for the ultimate robot.
Does your team have the budget for this? It is lots more expensive. Do you have the resources to develope the skill set to work with CF?
I think it is telling that the teams that have these requirements, don’t.
Maybe start with incorporating CF in places where it is a definite advantage and go from there.
There’s no such thing as everywhere. Your screws and nuts won’t be carbon fiber, right? Given that, making your drive shafts and gearbox components out of carbon fiber makes roughly as much sense.
There’s nothing inherently magical about carbon fiber, it has its uses in some parts but it is challenging to work with and the areas where it makes a ton of sense are somewhat niche. Large, very light, rigid structures can benefit from a touch of carbon fiber, sometimes, but that’s about it.
What safety measures is your head mentor implementing to make sure this shift doesn’t endanger the health of the team?
You are too humble and are spot on about the dangers. Handle with great care this dangerous material.
Notice the variety of problems and even a call for a
Write a local Risk Management Form (RMF) for the task. here
I would fear that students who as youths already think they are indestructible will not handle this material well and some of the ill-effects won’t be immediately obvious.
OP should try to understand the mentor being enamored with this technology. There is something going on there that we don’t know and can only guess.
This revolution could barely help a little to position the team with a competitive advantage in 5 years. Revolutions have the advantage of being able to be undone quickly so the team would have only the next season were they could not field a functioning robot and then revert to aluminum the following year.
I agree with all the other posters not to do this switch to CF. OPs team should do their soul-searching team meeting to discover why they aren’t a top-tier team and what they can do about it. Carbon fibers will NOT be one of the items on their list.
I’ve seen a mostly CF robot once.
It didn’t do all that well as I recall.
Ask the question this way: how many full spare chassis units are you going to need to bring to how many events? If CF breaks, and in FRC it will, it’s done. Swap it. It’s expensive, so there’s going to be a limit on how many you can build.
Everything said above about CF is correct and definitely something that you need to point out to your mentor and to your fellow team members when discussing this. But there’s also something else that needs to be brought up in this context:
It’s your team, not the mentor’s team, and ultimately the decision of what materials to use and what to build should rest with the team members.
This is something that is too easy for some mentors to overlook. But the essence of FRC is that we are just that…mentors, not CEOs or bosses or managers. It is the student team leadership and membership that should make the real decisions about what is built and how it is built. Mentors are there to provide continuity, experience and knowledge to help in that process. They are not meant, in the FIRST ideology, to be making the decisions on these things. No mentor should be pushing the team to pursue their personal choices about form, materials, code, or any other aspect of the robot. It’s your project and your decision.
I think it would be very helpful if teams that have successfully used CF would post their successful (and not so successful) use cases here as examples. Where have teams used CF on FRC robots in the past to great effect and what didn’t work out so well?
Seems like a great workshop video topic for someone with experience to create sometime. Where & how to use CF safely and effectively in FRC.
We are big fans of CF, but…
CF is not some magical material that makes the Robot a Super Robot. Pretty safe to say, a robot can be just as competitive made from that boring aluminum stuff. (i.e., 2910. I don’t think there was a lick of CF on that one and they seemed to do pretty good). From reading between the lines of the OPs post, I feel that the mentors might have a bit of Underpants Gnome Syndrome (UGS) happening.
Get some CF.
So, if wishing to use CF, where is it beneficial? For us it’s any structure that moves which is mainly elevators, arms, and manipulators. We have had pretty good luck using it in these applications with the only fatality being on our forearm in 2019 which destroyed any chance of getting off of Curie (That was kinda a big Ouchy). This failure was due to using a CF tube that had too thin a wall.
I can’t imagine using it in a frame. The impacts are too big and then there’s the headache on how to attach anything to it without drilling holes. (Drilling holes in CF is a big no no). CF remains this perfect, pristine material right up to the point it fails unlike aluminum or steel which first bends then cracks which gives you some warning that you’re pushing its limits.
So why use it?
Scientific reason: To reduce weight while maintaining stiffness in order to move the structure faster.
Educational reason: To experience using different materials and how to apply them.
Physiological reason: High coolness factor.
Successful ones off the top of my head that prominently used CF:
- 971 2018/2023 (arguably mostly carbon fiber I guess)
→ Also a lot of the 971-type arms in 2023
- 254 2023
- Most teams with buddy climbs in 2023 (254, 118, 5940, etc)
- 2018 (buddy climb)
- 118 2023 arm
Note none of them used cf for everything
254 has used composites a few different times in the past few years.
1/8" OD solid fiberglass rods pivot down actuator by pneumatic cylinders to smack the ball and make it settled before shooting in auton
Can Grabbers - 3/4" OD 1/16" wall CF tubes with custom layup CF triangular head in collaboration with 971
3/4" OD 1/16" wall tube with glued in tapped aluminum plugs for elevator carriage floor to slam cube when intake flips cube over to square it up
5/8" OD solid CF rods for buddy climb
3/4" OD 1/16" wall tube with glued in tapped aluminum plugs for intake standoff crossbar
5/8" OD solid CF rods for buddy climb no one got to see
3/4" OD 1/16" wall tube with glued in tapped aluminum plugs for intakes standoff crossbars
3/8" OD 1/16" wall tube clamped with 3D prints for shooter limelight a-frame mount
1" ID 0.04" wall square tube for Laterator (lateral elevator) and intake structure
5/8" OD solid CF rods for fork sneaky climb
(Dimensions are approximate based off my memory)
In general composites were used when we wanted maximum strength for minimal weight or size. The buddy climb forks, for example, were only 5/8" diameter which was good bit smaller than most others’ forks made to be 1" tall. Many teams had very easy time getting onto our forks because of this.
Composites work well in tension/bending, so were awesome as standoffs or buddy climb rods.
However, we learned this year with our Laterator that using square tubing for an elevator is much trickier. The Laterator tubes had holes drilled into them for attaching billet aluminum endplugs holding dowel pins that PEEK spacers rolled on. These holes would often wallow out. Because we had a 8lb intake on the end of this 3-stage lateral elevator, the tubes were in quite high bending load, especially during rapid accelerations / bouncing. We had some failures at home where the tubes would crack and we had to replace. Eventually we added 1" OD 0.030" wall aluminum round tubes inside all of the carbon fiber tubes, making them heavier but greatly strengthening them: we had no cracks/failures after adding the aluminum tubes.
I think I want to (or ask @BJC to) do a longer writeup on our Laterator another time. The conclusion though is that carbon fiber is tricky and you need to avoid adding any weak spots, better to clamp outsides than drill holes or put things inside.
Wait wait wait I’ve heard this joke somewhere before
I don’t know about this… mentors provide guidance and ensure decisions are made within the means and goals of the team. This could very easily go the opposite direction and have students demanding to use CF without the proper safety precautions or not knowing the limitations of CF within a design. To say nothing of the expense this can be for some teams who can barely afford it when it comes to composites.
Having had students wish to prototype what I term “death mechanisms” with insane gear ratios that offer no possible practical outcome for a successful season, yeah… I’m going to step in and stop them and put my foot down. I am more than a glorified babysitter in my role as a mentor. The place for that kind of thing isn’t a competition that costs what FRC costs and has the kind of timeframe and rigor that FRC has.
Hard disagree on this. Mentors provide experience and guidance from their own expertise and passions and if mentors have experience with writing Java code then I think a team should probably be using Java to provide their students with the best possible outcome. Same with composites - if a mentor has experience using composites and sees an application within an FRC challenge to use them, it might make sense to go that direction for a team and for those students to jump in and learn how to use them correctly.
Granted - every team is different and the level of discussion, type of process, team dynamics, and interpersonal communication used to build consensus are different too.
Back on topic…
We’ve used composites quite a bit but found, much like @Torrance mentions above, there are a lot of “there be dragons” markers on the map. It’s best to spend a fair amount of time researching how to use them correctly and what your outcomes are before going down a pathway of relying on them. We typically move to them when we recognize a weight issue and need to claw back savings on something that is being over-extended.
111 and 930 used a carbon fiber arm this year. 2614 tried to use carbon fiber in their arm but ended up having to use an aluminum arm.
111, 930, and 2614 all had very similar robots this year.
Take a look at 3669 - CarbonKnights. They build their robots almost entirely out of carbon fiber, which is really cool, and they’ve done a good job at making it their “thing,” but I’m sure they have some mentors with a lot of experience and knowledge in the field, not to mention the equipment and PPE to do it safely.
It’s also worth noting that they still lose to aluminum-based robots all the time, and that carbon fiber is not some silver bullet that can magically turn L’s into W’s.
930 used carbon fiber tubing for the arm.